Is 15" of vaccum good enough for power brake booster ?? 71 stock booster with front disc, brakes feel a little hard

Mine works at 15. How much do you have when you are decelerating? Its usually higher.

Mine works at 15. How much do you have when you are decelerating? Its usually higher.

checked it out Ive got 14 at idle in park and it drops to 10 in drive with brake applied

I've read many folks stating 15 - 18" of vaccum at idle. I have 8" at idle and am running a vaccum canister addon. I get 2 or 3 good stops at idle until I get a stiff pedal.

Need 18" vacuum for the brakes to work correctly.

I think you will be very happy with 14-15 " I am getting away with 10 "

13" at idle in park and a vacuum can here. Very happy with pedal feel.

I had 9" and the brakes worked...it was the absolute minimum. Another cam made 11", felt great.

Hi!
I just bought a vacuum gauge to check the p/b vac.
Where do I connect the gauge to get the right numbers ?
On the base plate of the carb or........?

:confused:

........

Hi!
I just bought a vacuum gauge to check the p/b vac.
Where do I connect the gauge to get the right numbers ?
On the base plate of the carb or........?

:confused:

........

Any manifold vacuum source (base of carb, port on intake, etc) will work fine.

OK! Thanks!

I have the same problem. My brake pedal also "feels hard".
The 350/165hp(L48?) is pretty much stock,eccept for the cam shaft that was put in.
I have no idea what it is,other than itīs a hydraulic flat tappet cam.
It has very choppy idle.
I guess a performance cam makes the vacuum drop,
Iīll give it a try tomorrow,and see what figures the vac.gauge shows.

I've got about 10-11 in my Elky. Pedal is hard. Works ok, not great. I would think 14 would be way better.

Yes, a choppy idle usually means low vaccum.